F44: Failure of Success Criterion 2.4.3 due to using tabindex to create a tab order that
does not preserve meaning and operability

Applicability

Description

This document describes a failure that occurs when the tab order does not
follow logical relationships and sequences in the content.

Focusable elements like links and form elements have a tabindex
attribute. The elements receive focus in ascending order of the value of the
tabindex attribute. When the values of the
tabindex attribute are assigned in a different order than the
relationships and sequences in the content, the tab order no longer follows
the relationships and sequences in the content.

One of the most common causes of this failure occurs when editing a page
where tabindex has been used. It is easy for the tab order and
the content order to fall out of correspondence when the content is edited
but the tabindex attributes are not updated to reflect the
changes to the content.

Examples

Failure Example 1

The following example incorrectly uses tabindex to specify an
alternative tab order:

If this list is navigated by the tab key, the list is navigated in
the order Homepage, chapter 3, chapter 2, chapter 1, which does not
follow the sequence in the content.

Failure Example 2

The tab order has been set explicitly in a Web page by providing
tabindex attributes for all fields. Later, the page
is modified to add a new field in the middle of the page, but the
author forgets to add a tabindex attribute to the new
field. As a result, the new field is at the end of the tab
order.